Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-61511

vBulletin < 6.2.2 Eval Injection RCE Remote Code Execution

vBulletin · 5.0.0 to <= 5.7.5

Watch CVE-2026-61511 Browse KEV feed
Severity
CVSS 9.3 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
5.6%
First observed
27 Aug 2026
Last observed
12 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-61511 is an unauthenticated vulnerability affecting vBulletin. vBulletin 5.x through 5.7.5 and 6.x through 6.2.1 contains an eval injection vulnerability in the vB5_Template_Runtime::runMaths() method within...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence.

Who is affected?

vBulletin 5.0.0 to <= 5.7.5.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

vBulletin < 6.2.2 Eval Injection RCE Remote Code Execution

vBulletin 5.x through 5.7.5 and 6.x through 6.2.1 contains an eval injection vulnerability in the vB5_Template_Runtime::runMaths() method within the template runtime that allows unauthenticated remote attackers to execute arbitrary PHP code by supplying crafted input through the pagenav[pagenumber] parameter.

Attackers can exploit the insufficiently restrictive regex filter by using phpfuck-style encoding with permitted characters to inject and execute arbitrary PHP code via the unauthenticated ajax/render template route without any authentication.

vBulletin Affected
vBulletin
Through 5.7.5 Through 6.2.1
vBulletin Unaffected
vBulletin
6.2.2
View vendor advisory (opens in new tab)
Published
27 Jul 2026
Exploitation Reported
27 Aug 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

php nuclei_scanner

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 27 Aug 2026

Previdian independently recorded this as exploited after first seeing it in honeypot sensors.

Active exploitation observed

Previdian sensor

First observed 27 Aug 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Proof of concept available

GitHub

Recorded 28 Jul 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
Previdian Sensors First 2026-08-27 13:06 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

9

Attempts observed

8

Unique attacker IPs

7

Attacker countries

BG · CH · FR · ID · SC · US · YE

7

Sensors observed

CVE-2026-61511 exploitation attempts over the last 53 days

Daily events observed by Previdian sensors

Updated 17 Oct 2026

0
1
1
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
0
0
0
1
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
26 Aug 6 Sep 17 Sep 28 Sep 17 Oct

First observed 27 Aug 2026 · Last observed 12 Oct 2026

Pro adds sensor region and window summaries. Enterprise adds raw IPs, paths, User-Agents, and payloads.

Start 14-day Pro trial

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
1
6
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

Learn about Pro API access

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-61511.yaml 25 Aug 2026

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

9.3 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

EPSS

5.6%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') CWE-95

All CVSS Scores

CVSS v4.0 9.3 Critical

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

vBulletin runtime template runMaths pre-auth RCE

pruva · Created 2026-07-27 17:08:26 UTC

Severity: CRITICAL | CVE: CVE-2026-61511 | Package: vBulletin

vBulletin runtime template runMaths pre-auth RCE

pruva · Created 2026-07-27 17:08:26 UTC

Severity: CRITICAL | CVE: CVE-2026-61511 | Package: vBulletin

SSD Secure Disclosure

cve · Created Unknown

vBulletin 6.x - Remote Code Execution

nuclei · Created Unknown

Karma(In)Security Disclosure

cve · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 12:46 UTC

    Indicators of compromise added (8)

    Indicators of compromise recorded

  2. 12:46 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  3. 04:31 UTC

    Nuclei template available

    Scanner coverage available

  4. 17:08 UTC

    Public PoC available

    Public proof-of-concept code published

  5. 12:39 UTC

    CVE published

    Vulnerability disclosed publicly

  6. 15:43 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-61511

Sample API response 
{
  "cve_id": "CVE-2026-61511",
  "confidence": "Confirmed",
  "cvss_score": 9.3,
  "cvss_estimated": false,
  "epss_score": 0.05607,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 9, "sensors": 7 }
}